Airflow Sensor Housing with Segmented Passages
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Solution Overview
Problem
Air flow rate measurement devices face accuracy issues due to dust contamination from burrs formed on mold parting marks in the housing, which can obstruct airflow and adhere to flow rate detection units, leading to errors in measurement.
Innovation Solution
The air flow rate measurement device is designed with a housing formed by injection molding, featuring a first sub-passage for dust discharge and a second sub-passage for clean air flow, with the mold parting mark positioned away from the inner opening edge of the first sub-passage outlet to prevent burrs from obstructing airflow and dust from entering the second sub-passage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the housing is formed by injection molding with a mold parting mark, then the housing can be manufactured efficiently, but burrs form on the mold parting mark which can obstruct airflow and adhere to the flow rate detection unit
Solution Approach 1:
The housing is divided into two separate sub-passages: a first sub-passage that allows dust-laden air to flow through and a second sub-passage that provides a clean airflow path to the flow rate detection unit. This segmentation prevents burrs from the mold parting mark from contaminating the measurement path while maintaining efficient injection molding manufacturing.
2Ease of manufacture
If the mold parting mark is positioned on the housing, then the injection molding process is simplified, but burrs from the parting mark can enter the sub-passage and contaminate the flow rate detection unit
Solution Approach 1:
The harmful effect of burrs from the mold parting mark is extracted and isolated by directing airflow through the first sub-passage that bypasses the detection unit. The mold parting mark remains on the housing for manufacturing simplicity, but its harmful byproduct (burs) is separated from the clean measurement path through strategic passage design.
3Device complexity
If a single sub-passage is used for airflow, then the device structure is simplified, but dust can adhere to the flow rate detection unit causing measurement errors
Solution Approach 1:
The airflow path is segmented into two distinct sub-passages within the housing: a first sub-passage that handles dust-laden airflow and a second sub-passage that delivers clean air to the flow rate detection unit. This segmentation maintains relatively simple device structure while ensuring measurement precision by preventing dust contamination.
Data Source
AI summary
A housing has a front surface, a rear surface, and side surface connecting the front surface with the rear surface. The housing is formed by injection molding. A first sub-passage is formed in the housing and communicates a first sub-passage inlet formed in the front surface with a first sub-passage outlet formed in the rear surface. A second sub-passage is formed in the housing and communicates a second sub-passage inlet formed in a midway portion of the first sub-passage with a second sub-passage outlet at a position different from the first sub-passage outlet. A flow rate detection unit is provided in the second sub-passage. A mold parting mark is formed in the rear surface of the housing at a position away from an inner opening edge of the first sub-passage outlet.